Spectral design of temperature-invariant narrow bandpass filters for the mid-infrared
12 January 2015
Our latest paper entitled 'Spectral design of temperature-invariant narrow bandpass filters for the mid-infrared' has just been published in the Optical Society of America, Optics Express journal. The paper is open access so anyone can download a copy.
Spectral design of temperature-invariant narrow bandpass filters for the mid-infrared
T Stolberg-Rohr, G J Hawkins
Optics Express, Vol. 23, Issue 1, pp. 580-596 (2015)
Abstract
The ability of narrow bandpass filters to discriminate wavelengths between closely-separated gas absorption lines is crucial in many areas of infrared spectroscopy. As improvements to the sensitivity of infrared detectors enables operation in uncontrolled high-temperature environments, this imposes demands on the explicit bandpass design to provide temperature-invariant behavior. The unique negative temperature coefficient (dn/dT<0) of Lead-based (Pb) salts, in combination with dielectric materials enable bandpass filters with exclusive immunity to shifts in wavelength with temperature. This paper presents the results of an investigation into the interdependence between multilayer bandpass design and optical materials together with a review on invariance at elevated temperatures.